Application of the invention lies with providers and operators of renewable energy and with installers of wind farms whether on dry land or off-shore.
The wind turbine nacelle of the invention is made by wind turbine manufacturers, or more generally by metal workers and/or mechanical welding businesses.
A wind turbine comprises in particular a tower, often also called a mast, a nacelle arranged at the top end of the tower, blades, and an alternator, said blades serving, under drive from the wind, to drive the rotor of the alternator in order to generate electricity. The blades and the alternator are arranged on the nacelle, which also includes other component elements of the wind turbine, in particular a system for braking the blades, and speed-increasing gearing.
Amongst wind turbines, there are upwind turbines; upwind turbines are constituted by blades located in a plane that is more or less vertical and designed to be exposed to face the oncoming wind directly. For this purpose, the wind turbine is fitted with an anemometer for monitoring the direction of the wind and a system for steering the nacelle that enables the direction in which the blades face to be modified depending on the measurements performed by the anemometer.
In the known prior art, the nacelle comprises a base and a head secured to the base. The head includes the alternator and the other component elements of the wind turbine, as mentioned above. In addition, it rotatably receives a hub that is secured to the rotor of the alternator and on which the blades are distributed.
The base is also mounted to pivot on the top end of the tower. This pivot mounting is achieved by means of a bearing laid flat on the top end of the tower, which bearing receives said base of the nacelle. By way of example, the bearing may be of the type comprising a ball slewing ring capable of supporting the combined loads exerted by the nacelle resting on the top end of the tower. This stewing ring allows the nacelle to pivot about a vertical axis corresponding to the vertical axis of the tower.
Furthermore, the system for steering a nacelle on the tower is arranged between the top end of said tower and the base of the nacelle, which nacelle incorporates the component elements of the steering system.
Such a design of wind turbine suffers from the drawback of requiring both the base of the nacelle and the top end of the tower that is to receive the ring to present excellent planeness so as to be able to receive between them the ball slewing ring.
In the known prior art, document WO 2007/125349 discloses a wind turbine having a nacelle mounted at the top end of a tower. The nacelle comprises a body and a head. The body has a conical top end that is extended upwards by a tubular chamber, said body being received via rolling bearings in a reception zone that is of shape complementary to said body and that is arranged at the end of the tower. The head comprises firstly a dish that enables blades to be mounted to rotate about an axis that is more or less horizontal and that serves to receive an alternator, and secondly a shaft that extends downwards and that is received in the tubular chamber of the body. A pivot connection constituted by the bearing is arranged between said shaft and said tubular chamber. Such a design presents the drawbacks of requiring the use of a tower that is designed specifically to receive such as nacelle. Such a design also increases the cost of making the tower so that it can receive the nacelle.